1. Field
The present disclosure relates to light emitting devices having an electrode structure for reducing series resistance and operating voltage, and methods of fabricating the light emitting devices.
2. Description of the Related Art
Semiconductor light emitting devices emit light by using the recombination of minority carriers that are injected through a p-n junction structure of a semiconductor. The semiconductor light emitting devices may be classified as light emitting diodes (LEDs) and laser diodes. The LEDs are considered efficient and environmentally friendly light sources because of their relatively high brightness and relatively low power consumption. The LEDs are used in various fields, including displays, optical communications, automobiles, and general lighting.
Light emitting performance is an important factor in regard to light emitting devices, and calculating light emitting efficiency is one way to determine the light emitting performance of light emitting devices. The light emitting efficiency may be determined by internal quantum efficiency, extraction efficiency, and operation voltage. The internal quantum efficiency is a characteristic representing how many photons are generated with respect to electrons transmitting through the light emitting device and may be determined by the quality of a semiconductor material and the design of an activation area. The extraction efficiency denotes a ratio of the generated photons with respect to the amount of photons extracted from a semiconductor chip. The photons may be absorbed into the semiconductor chip again while being internally reflected a plurality of times due to a difference between refractive indexes of the semiconductor material and peripheral material. Therefore, the extraction efficiency is limited by the photons that are lost during the multiple-reflection and absorption in the semiconductor chip. The operation efficiency is determined by an energy band gap in the activation area and an electric resistance of the light emitting device.